This is a great start, but needs a little more work to feel like a polished game. The key and door in the first room feel kind of perfunctory because the key is on the way to the door, so there's no real challenge to finding it. There's also no way to get to the end of the room without collecting the dog bone, so that doesn't feel like a challenge. The second room has a couple of very long corridors without much reason to pass through them, which seems a bit tedious. Then the skull sprite doesn't seem to relate to anything else in the game. Once you enter the third room there is no way to get out but no clear indication that the game is over, so it would be good to have something that definitively ends the game if it is the ending.